A trip to the Stadio San Paolo to face Napoli is a very tricky way for Liverpool to begin the defence of their Champions League crown.
With an inevitably thunderous atmosphere providing a backdrop, Liverpool must stifle threats of Dries Mertens and Lorenzo Insigne in attack while attempting to breach a defence led by the excellent Kalidou Koulibaly.
In midfield, there will be an opponent Jurgen Klopp knows all too well in Spain international Fabian Ruiz. Liverpool, along with Barcelona and Real Madrid, have been keeping tabs on the 23-year-old who has cemented his place as an integral part of Carlo Ancelotti's setup.
Sportsmail provides all the info you need on a player who has caught the eye of Europe's heavyweights.
WHAT SORT OF PLAYER IS RUIZ?
Napoli's No 8 is a versatile, left-footed midfielder who thrives with the ball at his feet, dictating the tempo and rhythm of his side. He's best in a 4-2-3-1 or 4-3-3 formation and his agent, Miguel Alfaro Garcia, has even said he believes Ruiz can play further forward, between midfield and attack.
But what makes Ruiz different to the traditional Spanish ball-playing midfielder that most people are familiar with is his size; at 6ft 2, Ruiz's physicality means the hard work of tackling opponents and holding off challenges comes easier to him.
WHO DOES HE STYLE HIMSELF ON?
He has previously said that Barcelona legend Xavi was who he looked up to as a youngster.
'I fell in love with football thanks to him,' the 23-year-old has admitted. 'He was a pillar for Barcelona and Spain for so many years and I dream of following in his footsteps.'
It will be music to the ears of the Barcelona boardroom if they do decide to turn their interest in him into a concrete offer.
HOW DID RUIZ END UP AT NAPOLI?
Ancelotti swooped for Ruiz in the summer of 2018, meeting his release clause of £26.7m at boyhood club Real Betis.
Ruiz had been at Betis since he was eight, leaving only for a loan spell at Elche in 2017.
Upon his return, he broke through into the Betis senior side and played a key role as they qualified for the Europa League in the 2017-18 campaign.
But, come the start of the following campaign, he was playing Champions League football under Ancelotti's guidance.
He featured in both matches against Liverpool in the group stages last season - he played 68 minutes in Napoli's 1-0 home win and 62 in the 1-0 defeat at Anfield that demoted them to the Europa League.
He played the full 90 minutes in both matches against Arsenal in the quarter-finals of Europe's secondary tournament but Napoli were defeated 3-0 on aggregate.
AND HE'S A SPAIN INTERNATIONAL?
As of June, yes.
He has two caps with the Spanish senior side to his name after making an appearance off the bench in the summer Euro 2020 qualifier against Faroe Islands before playing 90 minutes in the 3-0 win over Sweden.
He then joined up with Spain's Under 21 squad for Euro 2019 and played four times - scoring twice and providing three assists - as they won the competition. Ruiz was named player of the tournament.
SO IF HE DOES LEAVE NAPOLI, HOW MUCH WILL HE COST?
Reports in Italy earlier in September said that Napoli are looking to extend his contract after reportedly rejecting a £40m offer from Real Madrid.
Another season in Italy under a coach as astute as Ancelotti will do him no harm. If Napoli reach the Champions League knock-out stages and go the distance in a Serie A battle with Juventus, Ruiz will almost certainly play a central role.
In turn, it will take much more than £40m to get Napoli into negotiations next summer.
JUST HOW GOOD COULD HE BE?
Sergio Busquets compared Ruiz to his new Barcelona team-mate Frenkie De Jong only a few weeks ago.
'Both Fabian and De Jong have a great deal of quality,' said Busquets. 'Perhaps Frenkie still needs to adapt fully to the Barcelona style of play, but both represent the present and the future.
'I am sure they will become the best in the world in their respective roles.'
